This invention relates to monitoring circuits for a games and specifically to raster line comparators which compare display location to stored location instructions.
Video games are played using circuits which supply video and audio signal information to the antenna leads of a color television type display. Video information comprises background data; and fixed object data and movable object (called a "SPRITE" data. The fixed object data becomes a part of the background data for any specific game. SPRITE location and movable features location (and therefore data instructions) change from instant to instant as the game is played.
Additional predetermined trajectory or vector information can also be displayed according to the game played. This additional vector information can include moving "bullets", "missiles", swing vines, moving balls of all varieties and anything else the game inventor can think of.
It is important to display all of the game information accurately. One approach is to display the background in raster line fashion with background data instructions being provided for all 525 scan lines on the display screen. An object to be displayed, appears in front of the background and therefore is displayed instead of background information at that particular screen location.
A high speed comparator circuit is needed to switch the game circuitry from background to object data.
Video games find a marketplace either as a consumer item, or an arcade item. They need to use as little power as possible and be capable of being made as inexpensively as possible, i.e. be implemented with as little circuitry as possible.
An object of this invention is to provide a high speed raster location and column location comparator circuit.
A second object of this invention is to provide such a circuit which minimizes D.C. power use.
A further object of this invention is to provide such a circuit which can be implemented in LSI and NMOS circuitry in a minimal amount of silicon area.